Hanna Instruments HI784 Marine Ammonia Checker HC

The Hanna Instruments Marine Ammonia Checker HC (HI784) is a digital colorimeter that measures ammonia in your saltwater or reef aquarium far more precisely than a liquid color-card kit. Ammonia is the most dangerous compound for fish and corals, especially in a new tank, after adding livestock, or during a cycle, so an accurate reading matters. Instead of guessing between chart colors, the Checker gives you a clear digital number from 0.00 to 2.50 ppm. Browse more water testing and saltwater supplies at Squeaky's Aquatics.

Why Use the Checker HC

• Digital, not a color card: a fixed wavelength LED and detector read the sample, removing the eye strain and guesswork of matching colors.
• Reef-relevant resolution: reads 0.00 to 2.50 ppm of ammonia (NH3/NH4+) in 0.01 ppm steps, low enough to catch trouble early.
• Proven chemistry: uses an adaptation of the salicylate method; the reagent turns a blue-green tint the meter measures at 610 nm.
• Compact and simple: pocket-sized, one-button operation, with automatic shut-off after 20 minutes to save the battery.
• Built for marine tanks: designed specifically for saltwater aquarium and aquaculture use.

How to Use

1. Fill a cuvette with 10 mL of aquarium water, cap it, and place it in the meter to zero the reading.
2. Add the ammonia reagent to the same cuvette, cap, and gently invert to mix.
3. Press the button and let the timed reaction run, then read the ammonia value directly on the display.

What's Included

• Marine Ammonia Checker HC meter (HI784)
• Marine ammonia reagent starter kit (10 tests)
• Two sample cuvettes with caps
• Plastic refilling pipette
• 1.5V AAA battery
• Instruction manual and quick-reference guide

Specifications

Recommended Pairings

• HI784-25 reagent refills and other Hanna Checkers for nitrate, phosphate, alkalinity, and calcium.
• Water conditioners and ammonia detoxifiers to correct a high reading.
• Reef salt mix for clean, ammonia-free water changes.

Frequently Asked Questions

Is this for saltwater or freshwater?
It is designed for saltwater and reef aquariums (and marine aquaculture). Hanna makes a separate freshwater ammonia Checker for freshwater tanks.

How many tests come with it?
The starter reagent kit covers 10 tests. Refill reagents (HI784-25) are sold separately.

Why is it better than a color-card kit?
The meter reads the sample optically and shows a digital number, so you are not judging subtle color differences by eye, which is easy to get wrong at the low ammonia levels that matter in a reef.

What do I do if ammonia reads high?
Do a water change with clean saltwater, use an ammonia detoxifier, and check your cycle and stocking. Retest to confirm the level is dropping.